A 'Clear' Triumph at Box Office : Movies: The Harrison Ford thriller seizes the No. 1 spot with estimated ticket receipts of more than $20 million.

Harrison Ford, who has ignited the box office to the tune of $4 billion in tickets sold worldwide for such films as "Indiana Jones" and last summer's mega-hit "The Fugitive," apparently has done it again.

Ford's latest film, "Clear and Present Danger," collected an estimated $20.5 million over the weekend, making it the No. 1 film for the Friday-through-Sunday period.

The Paramount Pictures release, based on Tom Clancy's best-selling novel about drug trafficking in the United States, came into the marketplace with high expectations that it would be the summer season's last major hit film. It was expected to help the theatrical film business comfortably move through the typically sluggish late-summer dog days and maintain the moviegoing momentum that began with "Maverick" and continued with "The Flintstones," "Speed," "The Lion King," "Forrest Gump" and "The Mask."

All that, and more came to pass:

* The arrival of "Clear and Present Danger" helped produce what preliminary estimates indicated Sunday was the film industry's fifth consecutive weekend of $100-million-plus business, an unprecedented achievement.

* The figures from the just-ended weekend should push summer 1994 ahead of the record summer of 1993, which had included the megahit "Jurassic Park." The year-to-date total kept by Beverly Hills-based Exhibitor Relations Co. is 1% ahead of the total at this point in 1993.

Barry London, president of Paramount worldwide distribution, said he continues "to be amazed how the movie business continues to expand and accommodate multiple hits."

London said that with two well-attended nights of "Clear and Present Danger" previews prior to Friday's official opening, the box-office total for the film reached $29 million in five days. "What's impressive to me," said London, is that the film is achieving this level of ticket sales despite a running time of well over two hours, which limits showings at many theaters to four daily instead of the usual five.

In second place at the box office, in its second week of release, was the Jim Carrey special effects-laden comedy, "The Mask," which took in $15.5 million over the weekend.

Paramount's hit "Forrest Gump," starring Tom Hanks, was in third place, having made $165 million in 33 days of release. Over the weekend, "Gump" garnered $14.5 million. Between the Ford and the Hanks movies, Paramount's share of the market hit 35%.

Paramount Pictures Chairman Sherry Lansing took expected pride in the fact that two of the year's biggest films are from her studio. On Sunday, she said: "What's encouraging is that quality and commercial movies are going together."

Universal Pictures' release of "The Little Rascals" pulled a strong $10 million. The studio said the film was aided by a fondness among the public for the film's characters seen in early TV and in weekly movie theater serials.

Among other releases in the Top 10, "True Lies" added $9.2 million to bring its total to $100.8 million and a fifth-place finish.